1. Field of the Invention
The present invention is directed to a thrust plate assembly for a friction clutch including a housing having an axis of rotation and a pressure plate which is movable axially with respect to the housing by means of at least one leaf spring arrangement. The at least one leaf spring arrangement is secured in a first coupling area to a first mounting area of the pressure plate and is secured in a second coupling area to a second mounting area of the housing. A contact surface is provided respectively in the first mounting area and in the second mounting area at the pressure plate and housing for the contact of the at least one leaf spring arrangement with the first coupling area and the second coupling area.
2. Description of the Related Art
A thrust plate assembly of the type mentioned above is known, for example, from DE 198 48 582 and its basic construction will be described in the following with reference to FIG. 1.
This thrust plate assembly 10 shown in FIG. 1 has a housing 12, which is constructed at one axially open side for connecting to a flywheel or the like. A pressure plate 14 is provided in the housing 12 and, as will be described in the following, is arranged so as to be essentially fixed with respect to rotation relative to the housing 12, but so as to be displaceable in direction of an axis of rotation A. For this purpose, a plurality of leaf spring arrangements 16 are provided, each of which can have one leaf spring element, for example. The leaf spring arrangements 16 are securely connected by their end areas to the pressure plate 14 and housing 12, respectively, by rivet pins 24, 28 or the like. For this purpose, the pressure plate 14 has mounting portions 20 which project radially outward and at which the leaf spring arrangements 16 are secured to first coupling areas 11 by the rivet pins 24, or the like, mentioned above. The housing 12 has two mounting portions 18 formed by bending or shaping arranged so as to be offset in circumferential direction relative to the first mounting portions 20, the respective leaf spring units 16 being secured with the second coupling areas 26 by means of the rivet pins 28 or the like at these second mounting portions 18.
Due to the fact that the pressure plates 14 in thrust plate assemblies of the type mentioned above are generally offset in direction of the axis of rotation A with their first mounting portions 20 with respect to the second mounting portions 18 of the housing arrangement, the leaf spring arrangements and leaf spring elements thereof extend between the two mounting portions 18, 20 so as to be curved in axial direction. Particularly in friction clutches with a self-energizing or self-reinforcing engaging effect, this curvature is used to generate an additional force component pressing against a clutch disk during transmission of torque, a relatively sharp bend being required in the leaf spring arrangements 16 for this purpose. However, this results in a comparatively strong loading of the leaf spring arrangements particularly in their curved areas so that fatigue of the leaf spring arrangements results relatively quickly in these areas.
It is the object of the present invention to further develop a thrust plate assembly of the type mentioned above in such a way that the leaf spring arrangement or arrangements thereof is or are protected against excessive loading.
According to the invention, the contact surface in the first mounting area and/or the contact surface in the second mounting area are/is inclined relative to a plane extending essentially orthogonal to an axis of rotation of the thrust plate.
By providing the inclined contact surfaces which can be directly contacted by the leaf spring arrangements at the pressure plate and, as the case may be, at the housing, the leaf spring arrangements are already inclined in a direction in which they are also inclined in the final installation position. Nevertheless, a deflection of the leaf spring arrangements from their installed position results in the leaf spring arrangement generating a releasing force which draws the pressure plate back into the housing. The present invention provides a simple step by which overloading of the leaf spring arrangements is substantially prevented.
Preferably, it can be provided in the present invention that the contact surface is inclined along a line connecting the first mounting area and the second mounting area. In order to keep the loading of the leaf spring arrangements as slight as possible, the first mounting area and the second mounting area are offset relative to one another in the direction of an axis of rotation of the thrust plate, and the contact surface in the first mounting area and/or the contact surface in the second mounting area are/is inclined in such a way that the leaf spring arrangement contacting the latter extends substantially in a straight line toward the other mounting area in an essentially relaxed state of the leaf spring arrangement. In order to achieve a suitable support with the at least one leaf spring arrangement from both sides, particularly in the area of arrangement at the pressure plate, it is suggested that a correspondingly inclined counter-contact surface of a support element is located opposite the inclined contact surface in the first mounting area with the intermediary of the first coupling area of the at least one leaf spring arrangement. In this respect, it can further be provided that the pressure plate and the support element are oriented with respect to their surface regions remote of the contact surface and counter-contact surface, respectively, so as to be essentially parallel to the plane. By means of this step, it can be ensured that a rivet pin connecting the leaf spring arrangement to the pressure plate can be guided through an opening extending essentially in axial direction. It is not necessary to introduce any pin openings which are inclined in some way.
Additional protection against overloading of the leaf spring arrangement, especially during compression loading, can be achieved by means of apparatus for limiting relative rotational movement between the pressure plate and the housing such that the first mounting area and the second mounting area approach one another circumferentially. This rotational movement limiting apparatus can be achieved in a particularly simple manner with at least one shaped area which is preferably formed integral with the housing. In this case, the rotational movement limiting apparatus preferably forms a movement stop for at least one support element.
According to a further aspect, the present invention is directed to a thrust plate assembly for a friction clutch comprising a housing and a pressure plate which is held so as to be movable axially with respect to the housing by means of at least one leaf spring arrangement, wherein the at least one leaf spring arrangement is secured in a first coupling area to a first mounting area of the pressure plate and is secured in a second coupling area to a second mounting area of the housing arrangement. A contact surface is provided respectively in the first mounting area and in the second mounting area at the pressure plate and housing for the contact of the at least one leaf spring arrangement with the first coupling area and the second coupling area. This thrust plate assembly is characterized by apparatus for limiting the rotational movement of the pressure plate with respect to the housing such that the first mounting area and second mounting area approach one another circumferentially, wherein the rotational movement limiting apparatus provided at the housing and forms a movement stop for the pressure plate in the area of at least a first mounting area.
Excessive loading of the at least one leaf spring arrangement leading to compression deformation of the same is also prevented by providing a rotational movement stop of the type mentioned above which acts directly between the housing and the pressure plate.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.